After 10 episodes, the latest season of Doctor Who managed something no season of the show has pulled off since the series relaunch in 2005. As showrunner Chris Chibnall promised, not one single old-school alien from the show's 55-year-long history appeared onscreen. But the final episode of Season 11, "The Battle of Ranskoor Av Kolos," might have featured a blink-and-you'll-miss-it cameo from an entire alien planet. And, if it did, it's possible that 2020's Season 12 will finally conclude a long, complicated plotline that started back in 2013 (or 2005, depending on how you look at it).

**SPOILER WARNING: Spoilers ahead for Doctor Who Season 11.**

If you're new to Doctor Who this season and you watched the latest episode with a hardcore fan, they probably made some kind of happy noise when Jodie Whittaker boasted that the TARDIS "towed your planet halfway across the universe." And that's because the concept of moving or stealing a planet, specifically the Earth, actually happened in an epic David Tennant Season 4 story that ran through the entire 2008 season and culminated in the episodes "The Stolen Earth" and "Journey's End." (Retro recap: the Earth was stolen by the Daleks, and the 10th Doctor brought it back, just like the 13th Doctor said!) The point is, when it comes to planet-stealing, "The Stolen Earth" is the obvious reference, but it's not the most interesting one.

Instead, when it comes to the stolen or missing planets in the larger mythology of Doctor Who, there's really only one planet we should be talking about: Gallifrey, the home planet of the Time Lords and the Doctor herself.

Ever since a startling revelation from the 9th Doctor (Christopher Eccleston) in 2005's "The End of the World," the Doctor has been "The Last of the Time Lords," at least mostly. Throughout Seasons 1 through 7 of the contemporary series, references were made to the Time War (sometimes called "The Last Great Time War"), which resulted in the destruction of Gallifrey.

Eventually, we found out that the Doctor was responsible for this atrocity, but (supposedly) killed all the Daleks in the process, too. Then, in "The Day of the Doctor," the 10th, 11th, and War Doctors (David Tennant, Matt Smith, and John Hurt) managed to rewrite history and save Gallifrey by moving it into a pocket universe with the help of literally every other version of the Doctor who existed up until that point. (Including Peter Capaldi's then-new 12th Doctor in an eyebrow-raising cameo.) Notably, part of this plan involved all the Dalek ships blowing themselves up in a sudden crossfire, which happened because a giant planet sitting in between their spaceships suddenly disappeared.

Three Doctors fight the Daleks in "Day of the Doctor."

Now, in "The Battle of Ranskoor Av Kolos," way before it's discovered that Tzim-Sha had stolen entire planets, Graham (Bradley Walsh) and Ryan (Tosin Cole) defeat an army of killer robots by ducking and allowing those robots to be killed in a crossfire. Normally, the idea that Graham and Ryan took out some enemies with a crossfire switcharoo could be chalked up to a coincidence, but it seems like it's a subtle and very intentional reference to the crossfire from "The Day of the Doctor." Plus, the technology Tzim-Sha uses to steal planets is not unlike the stasis cubes from "The Day of the Doctor." Plus, the last time a planet was moved in Doctor Who wasn't the "The Stolen Earth," but instead when Gallifrey itself was saved in "The Day of the Doctor." Which leads us to the big question: Was one of the planets Tzim-Sha stole in "The Battle of Ranskoor Av Kolos," secretly Gallifrey? The visual evidence points to a big yes.

In the climax of the new episode, the Doctor is determined to harness the power of the Ux and transport each of the stolen planets back to their place of origin with the help of the telepathic circuits in the TARDIS. As the Doctor tells Yaz (Mandip Gil), "If it can work for your nani's watch, it can work for that clever lad." This references the previous Season 11 episode "Demons in the Punjab," in which the Doctor hooked up a watch belonging to Yaz's grandmother and allowed the telepathic circuits of the TARDIS to determine a destination by "reading" the place of origin from the thing itself. In this case, the TARDIS is figuring out where the stolen planets came from by reading the information in Delph's (Percelle Ascott) mind and zapping the planets back to where they belong. Relevantly, the Doctor never learns which planets these are, but the audience sees the funky stasis cubes popping up back in space as Delph succeeds.

Here's the thing: As the four stolen planets are returned to their rightful places in the universe, we only see one planet rematerialize completely. It happens in an instant, but that planet is golden-yellow-orangish, and totally looks like Gallifrey.

Gallifrey as depicted in "The End of Time."

So the questions are: Why bother to only depict one planet popping back into space and not the other three? Further, why make that planet look similar to Gallifrey if it wasn't supposed to be Gallifrey? Also, why bother to make the crossfire reference if Gallifrey wasn't secretly one of the stolen planets? The production design or VFX team on Doctor Who could have easily made that stolen planet a green planet with big rings, but they didn't. Writer Chris Chibnall could have had Graham and Ryan defeat those robots without referencing "The Day of the Doctor," but he didn't. Further, if Gallifrey was the planet the Doctor had strapped to her back — with grenades attached to it — it would add a great level of irony: The Doctor is always threatening to blow up Gallifrey, even when she doesn't know it's Gallifrey!

Anyway, for these reasons, it really seems like Gallifrey was one of the stolen planets and was placed back in the cosmos, possibly in its original location.

Why does this matter? Well, after "The Day of the Doctor," even though the entire planet was saved, the Doctor had a hard time finding it. In Season 8, Missy (Michelle Gomez) lied to the Doctor about the hidden planet's true location, and at the end of Season 9 in "Hell Bent," the Doctor returned to Gallifrey, which was hidden at the very edge of time and space. But, the thing is, when the 12th Doctor left Gallifrey in "Hell Bent," his memories were erased, which means we don't really know if the Doctor remembers where Gallifrey is hiding. Plus, between the events of "Hell Bent," and the start of Season 11, there's plenty of time for Tzim-Sha to have stolen Gallifrey and placed it in stasis.

If the Doctor just unwittingly stole it back and Gelph zapped it back to where it belongs, then that means the next season of Doctor Who could see the full return of a ton of Time Lords, resulting in a mild and complete retcon of pretty much everything that's happened to the Time Lords since 2005.

In other words, the Doctor Who Season 11 finale may have just casually ended the Time War once and for all. Of course, we won't know for sure until Season 12 hits in 2020. But, just like the Doctor, fans of this show are very, very patient.